In reply to Renato Godoy.

Certain independent watchmakers and service centers do have purchasing accounts with Rolex and are able to order many replacement components as necessary on a limited basis. For some components, the trade-in of the worn part is required before Rolex will sell a replacement. Not all watchmakers have direct accounts with Rolex and there are very strict requirements that must be met before Rolex will offer a watchmaker a parts account.
Because of how tightly controlled these parts are, there is definitely a secondary market for them - a quick internet search will yield numerous results for genuine replacement parts from various sellers around the globe. As far as verifying the authenticity of the components, this can be very difficult to do (especially if they have already been installed inside your movement). Consequently, having your watch serviced by a trusted and reliable watchmaker is just as important as buying it from a trusted and reputable source.